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gocurcon: Google Currency Converter Scrapper

PostPosted: Thu Jun 13, 2013 11:17 pm
by conan
Hi all,

I wanted to share a tiny script which allows me to query google/finance/converter from the CLI.

It's not much of a scrapper really, but I couldn't come up with a better word to describe it. It does scrap! Really! :P

Check it here:
https://github.com/conan-lugmen/newlisp-webscraps

I have two questions regarding my code:

1. Why unify requires uppercase tokens to be able to create symbols with bind? Or maybe my question is this one: Am I correctly using bind/unify? Is that the intended use?

2. I put a check to consider a get-url not giving back a proper answer. However on some runs I've noticed I get nil results like if my check was passed by. What am I doing wrong there?

Re: gocurcon: Google Currency Converter Scrapper

PostPosted: Fri Jun 14, 2013 6:18 pm
by Lutz
Using uppercase letters for variables in unification, is a convention introduced from logic programming with the Prolog language.

See also here: http://en.wikipedia.org/wiki/Unification_(computer_science)#Examples_of_syntactic_unification_of_first-order_terms

You are using bind with unify correctly, although instead of:

Code: Select all
(bind (unify '(From To Ammount) myArgs))

you could also use:
Code: Select all
(map set '(From To Ammount) myArgs))

and in the last case your variables don't need to be in uppercase.

Re: gocurcon: Google Currency Converter Scrapper

PostPosted: Fri Jun 21, 2013 11:45 am
by hilti
Thanks for this useful and small scraper.

Best wishes
Marc